Production of synthetic resinous materials by acid charring of lignins



Russell L. Sperry, Ojai, Calif.

No Drawing. Application March 30, 1956 Serial No. 574,992

23 Claims. (260-424) This invention relates to the production of synthetic chemical compounds from organic materials and their use in drilling muds to improve their properties.

One object of the invention is to produce novel, synthetic, organic compounds from those organic materials known as lignins, lignosulfonic acids, and salts and derivatives thereof, and also sometimes collectively called lignins.

Another object of this invention is to provide new and effective reagents for conditioning well-drilling liquid muds, more specifically clay-water base drilling fluids.

It is a still further object of this invention to produce high molecular-weight polycarboxylic acid compounds from the lignins, and to use acids produced therefrom, and alkali salts of such acids, in oil-well drilling muds for reducing water-loss during drilling, for reducing the viscosity of the muds, and for emulsifying oil therein.

A further object of the invention is to convert lignins, by acid dehydration or charring of the indicated raw materials, to black resin-like materials of relatively inert nature, it being also an object to convert such resin-like products by fusion with or digestion in water solutions of strong alkalis (more particularly the Group I alkali metal hydroxides) at high temperature to form the water-soluble alkali metal salts of corresponding acidic derivatives of the resin-like materials, it being also an object of the invention to prepare the free acids from the indicated salts, as by acidizing solutions of the salts, accompanied with the recovery of the acids, which are precipitated.

The term lignin is used to include the various types of lignin materials produced as side products by the pulp and paper industry. When wood chips are subjected to the action of the pulping liquor, the lignin present in the wood is largely dissolved, thereby freeing the fibrous cellulose. When the pulping liquor is alkaline, the lignin subsequently recovered from the liquor is known as alkali lignin. This serves to dilferentiate it from the lignin sulfonic acids and lignosulfonates which are recovered from the pulping of wood by the most common acid process, the sulfite process. The lignosulfonates are sometimes recovered as the alkali salts, particularly mixed calcium salts. The Indulins produced by the West Virginia Pulp and Paper Company are representative of the alkali lignins. The Marasperses produced by the Marathon Corporation are examples of the lignosulfonates.

I have discovered that lignins may be charred with strong mineral acids, more particularly sulfuric acid (including sulfur trioxide) and hydrochloric acid, preferably sulfuric acid, under controlled conditions to yield a black, resin-like, almost inert material, which, however, is largely made up of a product soluble in alkali metal hydroxide solutions at high temperature only, that is, in the neighborhood of 450 F. or above, e.g. up to 550 F. or 600 F. Whereas the acid-catalyzed destructive distillation of Unite States Patent lignins to a variety of organic compounds is well known, this invention relates to the almost quantitative conversion of the lignins, including the lignin sulfonic acids and lignosulfonates, to an intermediate black resinlike dehydration product, which in turn can be converted almost quantitatively to the alkali metal salts of black, high-molecular-weight polycarboxylic acids by fusion with, or digestion in water with, the Group I alkali-metal hydroxides at temperatures above about 450 F., such as 500 F. to 600 F. Although concentrated acids, such as fuming or 98% H are good for charring, concentrations down to 50%, 20%, and even lower, e.g. 5%, in the case of H 80 are usable, it being, however, necessary that there be sufiicient acid to, char the quantity of the organic portion of the lignin being treated. Whereas reaction with excess 80% or stronger sulfuric acid may be completed within a few minutes, charring with dilute acid mayrequire several hours ,at around F. to 200 F. 7

With reference to the charring of the lignins. according to the present invention, the term charring and the corresponding term char or char-resin signify the production of a black resin-like product by the respective strong acid employed, the treatment, however, not being carried to yield a largely free-carbon product but to yield a resinous reaction product, or dehydration product, which product is reactable with Group I alkali metal hydroxides (such as sodium hydroxide) to yield the described black alkali metal salts which are soluble in water and from which solution the described black, highmolecular-weight organic acids are precipitated upon acidification.

The indicated char resins are producible from the lignins by reaction with sulfuric acid under varying conditions of temperature and ratio of sulfuric acid to the organic lignin or the organic portion of the lignin, if a salt, within a range between about 150 F. and about 350 F. and ratios of about 0.2 part of acid to a. large excess of acid to one part of lignin. Whereas resin char may be formed almost instantly (vigorous exotherm) on reacting lignins with excess 80% or stronger sulfuric acid at about F. or above, practical application allows wide apparent variations of conditions. Where the temperature of reaction is in the lower range (about 150 F. to F.) and the ratio of sulfuric acid to lignin (organic content basis) is about 0.3 to 1 to 0.6 to 1, the time of reaction may be continued for many hours, such as 16 to 24 hours, without materially lowering the yield of desired product. However, as the ratio of acid to lignin is increased and/or the temperature is increased up to about 350 F., the time periods of heating are desirably decreased correspondingly, since otherwise the resin desired is slowly converted to carbonaceous materials which are not soluble in caustic solutions even at 500 F.

The use of dilute sulfuric acid is very advantageous, particularly when the raw materials are insoluble or only slowly soluble in acid solutions, since it allows uniform distribution of a low ratio of acid throughout the lignin.- Under these conditions evaporation of water to yield about 80% or stronger sulfuric acid and subsequent charring of the lignin takes place smoothly without uncontrollable exothermic reaction. The speed of the conversion can be regulated both by the actual temperature and therate of removal of water vapor from the zone of reaction.

Such procedures thus produce the required char resins which are reactable with Group I alkali metal hydroxides at the indicated high temperatures (about 450 F. to 600 F.) to yield the indicated black alkali metal salts from which the black high-moleculaflweig'ht water-im- .3 soluble organic acids may be obtained by precipitation from Water solution upon acidification. In reacting the char with alkali, the ratio of alkali metal hydroxide to char ranges between about f0.2 to 1 to about 1.3 to 1 one dryweight basis... Analyses and properties of the chars and acids derived from the various lignins indicate a striking resemblance to those derived by the same process. from carbohydrates (according to my patent application Ser. No. 558,620). Infrared analyses indicate that the acids derived from the lignins contain phenolic groups in addition to the carboxyl and hydroxyl groups present in the acids derived from the carbohydrates. Since some investigators report the presence of glucose and hydroxy methyl furfural among lignin decomposition products, the described reaction of the lignins may bereactions of modified carbohydrate groupings in the ligninmolecule although investigators seem to agree that lignins do not contain carbohydrate groupings as such. The structure of lignins has not been definitely established.

PROCEDURE The procedure as a whole involved in this improvement involves the several steps which principally include the following:

Step I.The lignin is charred with acid, preferably sulfuric acid or acceptably strong hydrochloric acid, under appropriate conditions.

. Step II.-The char may be crushed and washed with water to remove and recover residual acid.

Step [IL-The char, wet or dry, is mixed with a Group I alkali metal hydroxide such as sodium hydroxide, both the char and hydroxide being preferably powdered or crushed, or such powdered or crushed char is slurried in a. water solution of alkali hydroxide. By fusion of the char and hydroxide mixture (wet or dry) at a tempera ture of about 450 F. or above, such as 550 F. to 600 E; or by digestion of the water slurry of the reactantsin a pressure reactor at about 450 F. or above, such as up to 600- F., the char is converted to black water-soluble salts of high-molecular-weight organic acids. Such salts may be recovered from an aqueous solution as by evaporating to obtain substantially pure salts containing perhaps residual alkali metal hydroxide and carbonates.

Step lV.--Water solution of the sodium salts formed as above is acidified with mineral acid such as hydrochloric or sulfuric acids, or weak organic acids such as acetic acid, whereupon the high-molecular-weight synthetic acids, produced by the charring and the high temperature reaction with alkali, are precipitated at about 7 or lower pH. The acids are then isolated and washed with water to remove soluble materials.

When properly prepared from the commercial lignins and lignosulfonates, the washed and dried char requires a minimum of about 20% by weight of sodium hydroxide (or equivalent KOH or LiOH) based on the weight of the char to effect complete conversion of the char t the corresponding salts of the high-molecular-weight acids. The highest over-all conversion of the lignin to the corresponding black high-molecular-weight caids of step IV has been 88% based on the organic portion of the starting material. The char when properly prepared is insoluble or only slightly soluble in all the common solvents tested, and in 50% sodium hydroxide solution even up to 350 F., but does react with and become soluble in a water solution of sodium hydroxide at about 450 F. or above, as indicated above. Even at 450 F., the reaction is relatively slow and often requires an hour or more to go to completion. At about 500 F. or above, however, the reaction appears almost instantaneous (even with to 25% NaOH solutions) since complete solubility has been obtained in five minutes at 500 F.

Specific procedures under the various steps I through IV, as indicated above, are included in the following heated in an oven at 180 F. for 24 hours.

'4 examples which are summarized in table form to be more readily understood:

Group I.Preparation of resin-chars and high-molecularweight acids therefrom using low temperatures and low ratios of acid to lignin in step I The yields of resin and acids derived from the indicated lignin given in Table I were obtained by the following procedure: The lignin was uniformly wetted with 1% times its weight of 43% by weight sulfuric acid, giving a variable ratio of H to the organic portion of the lignin (about 0.8 to 1 for Indulin A up to about 1:1 for Marasperse C). The treated lignin was then The result ant char was crushed and slurried in water, filtered, washed thoroughly with boiling water, and dried at 125 C. The char was then slurried in about 4 times its weight of water containing 60% NaOH based on the weight of the char. The slurry was heated in a pressure reactor for 15 minutes at 490 F. to 520 F. The resulting black solution was filtered to remove traces of insolubles. The filtrate was diluted and acidified with hydrochloric acid. The resultant flocculated acids were recovered by filtration and thoroughly washed with water to remove residual salts and acid. The filtrates in all cases were colorless to very pale yellow in color. The recovered black acids were dried at C.

The various Indulins and Marasperses of the above list are convenient examples of suitable lignins for the present method. The Indulins are produced by West Virginia Pulp and Paper Company of Charleston, South Carolina, and the various Marasperses are produced by the Marathon Corporation of Rothschild, Wisconsin. It is stated that Indulin A is a purified pine wood lignin derived from paper-pulp sulfate black liquor containing over 99.5% organic material; is a brown free-flowing amorphous powder, insoluble in water and acids, and soluble in alkali solutions; and normally has a pH running between 3.0 and 4.5. Indulin B is a purified sodium salt of pine wood lignin, containing about 4.0% sodium, which lignin is separated from paper-pulp sulfate black liquor; is soluble in water and alkali but insoluble in acids; and has a pH range from8 to 9. Indulin C is a crude sodium'salt of pine wood lignin, containing about 10% sodium, which lignin is separated from paper-pulp sulfate black liquor; is a brown free-flowing amorphous powder containing some occluded black liquor; and has a pH range from 9 to 10. The listed Marasperses con representatives found on the market of various lignins,.

lignosulfonic acids, their salts and other derivatives thereof, included within the general term lignins of this application and usable. for thepresentpurpose.

Group Zl.-Preparati0n of resin-chars and high-m0lec-- ular-weight acids using excess concentrated acid and allowing a short time high-temperature exothermic action w The yields. of resins and acids from the indicated lignins. given in Table H wereobtained by proceduresidentical to the above with the following exceptions:

Thelignin was slurried in about twice its weight of 96% sulfuric acid. The slurry blackened, expanded in volume, varying amounts of S were evolved, and the temperature rose exothermically to above 200 F.

In order to show the valuable characteristics of the synthetic salts and acids of this invention, comparative tests with standard drilling mud reagents were run simultaneously. Such reagents have been indicated in the In all cases reaction appeared complete in 10 to 15 following tables as: a minutes. (1) Cypan, which is a sodium polyacrylate marketed (2) The char was converted to black soluble salts using by the American Cyanamid Co., and is a very active 40% NaOH based on the weight of the char. water-loss control reagent; it is a non-emulsifier by usual T StandardS.

(2) Quebracho, which is a tannin in general use in Percenimcoggy Percglrt g ggg all(t3:3;pcsL of dr1lh:i1g ilimds:i also ad non-emilsifiler. l

ar-res ee 0 ignite, me an groun is use in arge voiii fi i iiifi fiia g; 295 ume as an emulsifier, particularly in higher pH (9 to 13) muds and in lime muds. ndunn A" 83 86 15 All tests were run by adding the indicated number of 23311313-. 3 3% grams of reagent to 350 cc. of the prepared mud, these fu gfij I 64 34 amounts being the equivalent to the same number of pounds per 42-gallon barrel of mud. Such treated mud p e in each test was then heated with agitation (rolls) in a a closed vessel at 160 F. to 170 F.'for 16 to 24 hours. Group lll" prepamtwn of f z My of the black The water-loss was run on the hot mud by the standard 1 molecular tact s A.P.I. 100 lbs./sq. in. method, the water-loss recorded, Preparations using both general methods indicated in F Of filtrate in 15, and minutes Th V Groups I and II above were carried only to the-sodium 116$ P Present 11111130565 are Tecm'ded as thick, medium, .salt stage. The solutions of the black salts were evap- 25 1 5 7 orated to dryness at 105 C. for testing in drilling muds. T s s are Presented 111 $61168 the Partiwlar The yields of water-soluble salts ranged between 92% lndlcatfid muds, a blank e tests W h e elland 100%+ based on the total weight of the char-resin known control reagents being elven first, followed y d Group I lk li t l h d i m tests with the products of this invention derived from the indicated lignins. .The free acids, designated by X Y DRILLING MUD TREATMENT. in these tables, were prepared according to Group I or The use ofthe synthetic acids and their sodium salts II methods above, and were predissolved in calustic soof'this invention for treating drilling muds will be underlution as indicated. Where the products of this invenstood by those skilled in the art from the results supplied tion are designated as NaX, the salt was prepared acby the following examples. Such high-molecular-weight cording to Group III above, and contained any soluble synthetic products are shown to be eifective in various impurities formed in the preparation. Forcomparison types of clay-water-base muds and oil-in-water emulsion also, tests with three of the lignins, from which the muds as commonly used by the oil industry. For testing products of this invention were prepared, are included purposes two basic types of clay-base muds have been at the end of Series I and II. employed: 40 l Low p to gyp salbcontaminated Use of sa is and acids In drzllmg muds mud made up by hydrating a good commercial bentonite SERIES 1 clay in gypsum-saturated, salt-contaminated water. Commercial P- clay was hydrated 24 hours with (2) High pH (10-13) lime mud prepared byadding gypsum saturated water containing about g.p. g. lime and caustic to any clay-base drilling mud alongwith 45 (g p gallon) Nacl- The mud was adjusted t lignite, quebracho, or other similar reagent, in amount 84 lbs/ cu. ft. Each reagent or combination of reagents suflicient to maintain suitable viscosity, gel, and waterindicated was predissolved in 10 cc. water, which was loss characteristics. also added to the blank mud. The samples were heated Oil may be added to either of the above muds toform at F. to F. with agitation for 20 hours as oil-in-water emulsion fluids. 5 v 5 indicated above and tested.

cc. Water Loss, A.P.I., Test minutes No. Gm. Reagent Acids source Viscosity pH 1- 14.8 21.4 29.8 Thlck 8Z2 2 f ggfigggk 7.0 10.5 14.0 Thin 10.7

833535321 12.8 18.3 25.8 Medlum- I 10.3 4 gg ggggigt as 5.2 7.8 Th1ek 8.4 5 f IndulinA a7 5.8 8.6 Thin 10.1 e 2 3.8 6.0 9.0 Thin 10.2 7 f }1ndui B 4.15 0.5 9.2 Thin "10.0 8 f }1ndu1ino 5.1 j 7.5 10.8 Medium; 10.2 9 f }Ma.rasperse o....- 4.1 V 5.8 7.9 Thi 11 .0 10-.-- I a Marasperse 0----- as 5.0 7.0 Thin 9.6 11-.- }Marasperse on-.- 6.0 8.6 11.1 Thin 9.0 12" }Mar8sperse N 4.8 6. 7' 9. 9 Medium" 10. 1 2 }Commercial 11.6 16.8 24.3 Thick 0.7 14-.;..{ 2 }Commercial 12.4 17.8 25.6 Thick"..- 9.7 15.-...{ }Commercial 11.0 16.8 24.0 Thick..--.' 9.0

In addition to the value of the prepared acids and alkali salts thereof for controlling the viscosity and including the filtrates and wall cakes which were redispersed in eachinstance; 10% by volume (35 cc.) of

32 gravity Yentura crude oil was added to each sample; the samples were reheated with mild agitation at 160 F. to 170 F. for four to five hours; and the samples again tested for Water loss and the presence of free oil with the following results:

, ccl Water Loss, A.P.I., 30 min. water minutes loss above Results before adding oil (00.) 7.5 15 3O 1AExcess tree oil 13.0 18.8 26. 6 (29. 8) 2AExccss free oil 7. 3 10.0 13. 2 (14. 3AS0me free oil 9. 2 13.2 18. (25. 8) 4A-Excess tree oil 3. 2 4. 6 7. 2 (7. 8)

1 5A-Some free oil. 3.0 4. 4 7. 2 (8. 6) (EA-Some free oil. 3. 3 5. 0 7. 0 (9. 0) 7A-Some free oil 3. 4 5.4 7.8 (9. 2) 8A-Trace 1'1 ee oi 4. 0 5. 9 8. 3 (10. 8) 9A-Trace free 01 3.0 4. 6 7. 4 (7. 9) 10ATrace tree oil. 3. O 4.3 6. 6 (7. 0) llA-Trnce free oil 5.0 7. 3 10.2 (11.1) 12ASome tree oil 4. 1 5. 8 8. l (9. 9) 13A-S0me free oil 8. 0 11. 6 17.0 (24. 3

' 14A-Sornefrec oil 9. 9 l4. 4 21.2 (25. 6)

. 15A-Some free oil 9. 2 13.2 18. 4 (24. 0)

SERIES NO. 2 The potential value of these products for treating lime muds is indicated by the following test results. A sample of lime mud from a well in Ventura, California, of Tidewater-Associated'Oil Co. was diluted with 10% of its volume with water. Samples were treated with the indicated reagents, heated with agitation as above for 16 hours and tested as above. The sodium salts of the acids of this invention were obtained by drying acids and alkali salts of the synthetic acids formed from the lignins have considerable activity for control of viscosity and water-loss of drilling mudsQand for emulsifying oil therein. In field practice, other organic acidic materials such as tannins and lignites are sometimes added directly to drilling muds. However, more generally such materials are predissolved in caustic solution in the proper ratio to obtain the desired pH control of the mud. The acids of this invention similarly may be used in either way. Obviously, the use of the sodium salts recovered directly from the fusion step would afford the lowest cost product.

In any case, since the pH of the mud is generally above about 7.5, the acids are present in the mud in salt form, and the activity is then effectually a measure of the activity of the soluble salts formed in the mud.

Especially from the following series of tests, it will be noted that the greater the proportion of the given acid or its alkali metal salt employed, the lower is the water-loss. This is especially true in the range of about lb. per barrel to 6 lbs. per barrel of salt in the mud and continues up to about 10 lbs. per barrel in laboratory muds. As is well known to those trained in the art, the concentration of a reagent required to produce a desired effect on a field mud will vary extremely with the type of mud and the particular effect desired. As much as 20 lbs. of these reagents per barrel of mud might prove advantageous to emulsify 20%, 30%, or oil in the mud, to overcome extreme salt or gypsum contamination, or in preparing lime muds of extreme lime concentration. Therefore, the effectiveness of a reagent can be proven by laboratory tests, but an upper limit of practical concentration cannot be established by the effect on any one mud.

SERIES N0. 3

Tests run as usual (above) on 84 lbs/cu. ft. P95 hydrated in hard water.

cc. Water Loss A.P.I. Test Gm. Reagent Acids Source minutes N o. Viscosity pH 1 14.8 21.4 29.8 Thick 8.2 1 2 9.8 14.3 21.0 Medium. 0.4 a }IndulinA 4.5 0.3 0.0 Thi11 10.2 4 }Indu1inA 3.6 5.1 7.3 Thin 0.7 s Marasperse o. 9.2 13.2 18.7 Medium.. 0.7 0 f {Maraspersc o. 4.7 6.5 9.1 Thin 0.0 7 {Maraspersc o- 3.2 4.6 7.0 Thin 10.2

the solution obtained by digesting the indicated chars with 40% by weight NaOH (according to Group III above).

I claim as my invention: 1. A method for producing high molecular-weight synthetic organic acid materials, including: charring lignin cc. Water Loss, A.P.I., Test No. Gm. Reagent Salts Source minutes Viscosity pH niai nn n sis 5.4 7.8 Medium.... 12.2

ue r00 0-- omnicrcia g g fi 2.7 as 5.7 Very thin.-- 13 OmmGIOIE U.

CommerciaL 2. 9 v 4. 1 6.1 Thin 131: Marasperse 1.7 2.8 74.2 Thin... 12.0 Indulin A 2. 5 3.6 5. 2 Thin 12.1

The above mud was in use while drilling at about 11,000 materials with an acid selected from the group consistbeen used. i

It is apparent from the above results that the free ing of sulfuric acid, su lfur trioxide and hydrochloric acid in amount between about 0.2 part and an excess of acid .on. a water-free basis per part of lignin material, such char-ring being produced at charting temperatures below about 350 F. to yield a black resin-like product which is substantially insoluble in boiling alkali metal hydroxide solutions, but reacts with and becomes soluble in alkali metal hydroxides at temperatures above about 450 F. to yield water-soluble alkali metal salts of high molecularweight organic acids; and digesting said resin-like char with alkali metal hydroxide at temperatures above about 450 F. and thereby forming alkali metal salts of said high molecular-weight organic acids.

2. A method as in claim 1, wherein charring with acid takes place at a temperature between about 150 F. and 350 F.

3. A method as in claim 1, wherein the charring temperature approximates 170 F. to 185 F.

4. A method as in claim 1 wherein reaction with the alkali metal hydroxide takes place in a temperature range approximating 450 F. to 550 F.

5. A method according to claim 1, including washing the char with water prior to the alkali treatment.

6. A method according to claim 1, wherein the acid is sulfuric acid of at least about 80% concentration.

7. A method according to claim 1, wherein the acid is sulfuric acid initially below 80% concentration.

8. A method according to claim 1, wherein the acid employed is present in an amount approximating about one-third part to about one and one-half parts by weight on a water-free basis per part of organic portion of the lignin material, and the acid treatment is continued from about one-fourth to about fifteen hours.

9. A method as in claim 1 including the additional step of producing a water solution of said alkali metal salts of said organic acids and acidifying said water solution to precipitate said organic acids.

10. A method as in claim 1, wherein the digestion of the char with alkali metal hydroxide is conducted between about 500 F. and 600 F.

11. A method as in claim 1, wherein the charring reaction occurs without substantial conversion to free carbon and the char is substantially insoluble in alkali metal hydroxide up to 350 F.

12. A synthetic alkali metal salt of said high molecularweight organic acids produced by the process of claim 1.

13. A synthetic high molecular-weight carboxylic acid produced by the process of claim 9.

14. A method of producing salts of high molecularweight organic acids including: charring with sulfuric acid lignin materials at temperatures between about 150 F. and 250 F. to yield a resin-like char insoluble in alkali metal hydroxide up to 350 F., and soluble in alkali metal hydroxide at temperatures above about 450 F. to yield water-soluble alkali metal salts of polycarboxylic acids; and reacting said resin-like char with alkali metal hydroxide at temperatures above about 450 F. and thereby forming alkali metal salts of said polycarboxylic acids.

15. A method according to claim 1 wherein the lignin containing material is a wood product.

16. A method according to claim 1 wherein the lignin containing material is recovered from a liquor used in a wood pulping process.

17. A method for the preparation of high-molecularweight synthetic organic materials including: charring lignin materials to char resins with sulfuric acid at temperatures between about 150 F. and 350 F. to yield a char substantially insoluble in alkali metal hydroxide below 350 F. and soluble in alkali metal hydroxide above about 450 F. to yield water-soluble alkali metal salts of polycarboxylic acids; and reacting the resultant char resins with alkali metal hydroxides at temperatures between about 450 F. and 600 F., yielding watersoluble alkali metal salts of high-molecular-weight organic acids, the ratio of the sulfuric acid to the organic portion of the lignin material on a dry basis being in a range of about 0.3:1 to about 15:1, and the ratio of alkali metal hydroxide to char resins on a dry basis being in a range of about 0.2:1 to 1:1.

18. A method as in claim 17 including the additional steps of acidizing a water solution of the black alkali metal salts produced to precipitate the high-molecularweight acid constituents, and recovering the precipitated acids.

19. A method of producing synthetic, high-molecularweight organic materials including; charring with sulfuric acid lignin materials, the sulfuric acid being at least as concentrated as about by weight and the temperature of reaction being controlled above about F. and below about 350 F., the ratio of sulfuric acid to organic portion of the lignin material being above about 03:1, and the time of reaction varying from a few minutes at the higher temperatures and acid ratios to one to twenty-four hours when the lower acid ratios and temperatures are employed, thereby producing black, water-insoluble resin-like organic materials which are insoluble in solutions of alkali metal hydroxides below about 350 F., but react with and become soluble in Water solutions of the alkali metal hydroxides above about 450 F reacting said resin-like organic materials with alkali metal hydroxide at temperatures above about 450 F. and below about 600 F., the ratio of alkali metal hydroxide to organic resin on a dry basis being in a range between about 0.2:1 and 1:1; and recovering the resultant water-soluble alkali metal salts of acid constitutents.

20. A method according to claim 19, wherein the lignin material is treated with sulfuric acid of less than about 80% by weight concentration and with heating above about 150 F. resulting in loss of water, conversion to black synthetic organic material commencing as the concentration of the sulfuric acid becomes above about 80% by weight.

I 21. A method according to claim 19 including acidifying a water solution of said salts to precipitate synthetic organic acids, and recovering such organic acids.

22. A method as in claim 19 wherein the lignin material is alkali lignin.

23. A method as in claim 19 wherein the lignin material is a lignosulfonate.

References Cited in the file of this patent UNITED STATES PATENTS 1,149,420 Strehlenert Aug. 10, 1915 2,280,600 Muller et al. Apr. 21, 1942 2,477,157 Wayne July 26, 1949 2,640,052 Stoddard May 26, 1953 2,680,113 Adler et al. June 1, 1954 2,702,787 Freeland Feb. 22, 1955 FOREIGN PATENTS 202,132 Germany Sept. 29, 1908 

1. A METHOD FOR PRODUCING HIGH MOLECULAR-WEIGHT SYNTHETIC ORGANIC ACID MATERIALS, INCLUDING: CHARRING LIGNIN MATERIALS WITH AN ACID SELECTED FROM THE GROUP CONSISTING OF SULFURIC ACID, SULFUR TRIOXIDE AND HYDROCHLORIC ACID IN AMOUNT BETWEEN ABOUT 0.2 PART AND AN EXCESS OF ACID ON A WATER-FREE BASIS PER PART OF LIGNIN MATERIAL, SUCH CHARRING BEING PRODUCED AT CHARRING TEMPERATURES BELOW ABOUT 350* F. TO YEILD A BLACK RESIN-LIKE PRODUCT WHICH IS SUBSTANTIALLY INSOLUBLE IN BOILING ALKALI METAL HYDROXIDE SOLUTIONS, BUT REACTS WITH AND BECOMES SOLUBLE IN ALKALI METAL HYDOXIDES AT TEMPERATURES ABOVE ABOUT 450* F. TO YEILD WATER-SOLUBLE ALKALI METAL SALTS OF HIGH MOLECULARWEIGHT ORGANIC ACIDS; AND DIGESTIN G SAID RESIN-LIKE CHAR WITH ALKALI METAL HYDROXIDE AT TEMPERATURES ABOVE ABOUT 450* F. AND THEREBY FORMING ALKALI METAL SALTS OF SAID HIGH MOLECULAR-WEIGHT ORGANIC ACIDS. 